Jean-Baptiste Leca, Ph.D.

Current and main research activities

I study behavioral innovations and cultural traditions
in non-human primates. This topic intrigues psychologists and biologists alike
because culture is a social (rather than genetic) means by which traits can be
inherited. I aim to shed light on how cultural behavioral patterns originate,
spread, and are maintained or may change over time, by studying proximate
(i.e., genetic, environmental, cognitive, demographic, social) and ultimate
(i.e., adaptive, phylogenetic) influences. My research projects address the
biological, psychological and ecological foundations of behavioral traditions
in Japanese macaques and long-tailed macaques in order to better understand
the role of cultural processes in human evolution. In a nutshell, I am interested
in the hows and whys of cultural behaviors in monkeys.

While most primate cultures are considered adaptive – like
chimpanzee tool use – I explore the proximate and ultimate causes of
non-adaptive or questionably adaptivebehavioral traditions. By focusing on
such exceptions to the rule, my research contributes to further our
understanding of evolutionary processes and the variety of behavioral patterns
they produce.

Material culture in long-tailed macaques

Currently, my research team members and I are
developing three complementary projects that explore group-specific (and thus
potentially cultural) behavioral patterns in free-ranging Balinese long-tailed
macaques.

More specifically, we are investigating the development, mechanisms
and possible functional components of:

stone handling/play

eye covering play

object robbing and object/food bartering practice

as well as complex extractive foraging (e.g., coconut bashing) and
tool-assisted foraging in this primate species.

Non-conceptive sex in Japanese macaques

Simultaneously, I am continuing to study
non-conceptive (socio-)sexual behaviors in female and male Japanese macaques
from a longitudinal and intergroup comparative perspective:

immature play
mounting

female-male mounting

male masturbation

monkey-deer mounting

social dynamics of all-male groups

My long-term goal
is to extend my research on non-adaptive cultural behaviors to other macaque
species and use these comparative analyses to model the forces that have shaped
our own culture during the course of human evolution. In doing so, I will
investigate how seemingly non-adaptive behaviors may lead to adaptive outcomes
for the individual, the group, and the species.

The following items summarize these different
ongoing research projects.

STONE-HANDLING/PLAY CULTURE IN JAPANESE MACAQUES AND
BALINESE LONG-TAILED MACAQUES